pc smps torroids

[p.larner]

can the torroids from scrap smps units be used as common mode chokes at hf?.

[madires]

The common mode chokes in SMPSs are meant to filter frequencies up to the lower radio frequency bands. Which frequency bands do you mean? And how much RF power?

[Andy Chee]

If you're talking about the SMPS toroids that I'm thinking of (typically yellow enamel coating), then no, those toroids will not work.  That's because they are made of powdered iron which is the incorrect material.  You need ferrite material for a common mode HF choke. 

If you want to salvage ferrite, look no further than scrap VGA monitor cables.

Incidentally, you can use your VNA to measure an unknown toroid's parameters.  Then you can compare the graphs to a known #31 or #43 or #76 ferrite datasheet.

https://owenduffy.net/blog/?p=5198

[p.larner]

i was thinking of 10w max from 80-10m

[madires]

Look for ferrite material 73.

[p.larner]

i am not worried enough to hunt for them as have no rf issues feedback etc,its just i have a bunch of dead smps units and wondered if the torroids were of use for ham radio.

[madires]

If you're talking about the SMPS toroids that I'm thinking of (typically yellow enamel coating), then no, those toroids will not work.

The yellow ones (with a white side) are material 26, good for up to about 1MHz. Because of the iron powder (distributed air gap) they are great for DC/DC converters.

[A.Z.]

i am not worried enough to hunt for them as have no rf issues feedback etc,its just i have a bunch of dead smps units and wondered if the torroids were of use for ham radio.

how can you say you have "no RF issues"; did you take some MEASUREMENTS ?

https://owenduffy.net/blog/?p=458

https://owenduffy.net/module/icm/index.htm

If not, then what are you talking about ?

As for those iron powder toroids, yes, you can use them for an ATU, and a pretty good one too

https://pa0fri.home.xs4all.nl/ATU/FRImatch/FRImatcheng.htm

but for sure, not for baluns/chokes, the material doesn't fit the requirements, you'll need NiZn or the like, plug in the brain and gather some infos

http://www.karinya.net/g3txq/chokes/

https://gm3sek.files.wordpress.com/2019/01/G3TXQ-RC.pdf

and, this time, try to UNDERSTAND things

P.S. the spelling is "toroids" not "torRoids"

[coppercone2]

yes,if you crack the code then millions of pounds of junk boxes will suddenly gain some value

we have been waiting at least 30 years for this moment. Otherwise i predict they will be inert until the discovery of the alternate topology subspace repeater made by people some where around 3000 years from now.


maybe its possible to strip the coating and crystalize some kind of material in there under the correct conditions to utilize them. With high pressure fed electroplasmic deposition reactors. Only possible for cores aged at STP for at least 25 years.